Total size for the Survey Line Fire on Fort Wainwright was estimated at 61,500 acres Monday, said Andy Williams of the Alaska Interagency Coordination Center.

The Fish Creek Fire, further south, was officially logged at 31,000 acres, "but it appears the fire is bigger than that," according to Pete Buist of the state Division of Forestry.

The fire on Wainwright had been allowed to burn essentially unchecked since it began Wednesday. But a couple of eight-person smokejumping crews were working to contain a couple of spot fires Monday. One was dispatched to a hot spot where the fire crossed the Wood River at the western edge of the burn area. The other was on an island in the Tanana River, which has contained the blaze on its northwest flank.

A helicopter crew also set fires along the western bank of the Wood River to keep the wildfire from crossing that barrier, Williams said.

The Fish Creek Fire further south was very active and moving eastward after the wind shifted 180 degrees, said Buist of the Forestry Division.

"Except for the northwestern corner, virtually all of the fire perimeter is active," said Buist. The fire was moving east of the Totatlanika River, in an area where fires are allowed to burn. It is, indeed, an area where the division was planning some prescribed burning to improve the habitat for moose, Buist said.

If the fire moves a few miles further east, it could threaten some homes and private land at Gold King, he said.

"We have taken some action to slow or stop the spread" in that direction, Buist said. Nearly 300 firefighters were battling that blaze, which also started Wednesday.

Both of the big fires started along a utility corridor being cleared for a major and controversial power line across the flats to link Healy and Fairbanks.